In the manufacture of wings for large aircraft, the wing components, including the wing skin panels, the spars, the ribs and other major components are typically partially assembled in a jig which holds those components in the desired alignment whilst holes for fasteners are drilled in predetermined locations by an automated machine. Slave bolts are then inserted in some of the holes to hold the wing assembly together whilst further fastening operations take place.
For manufacture of wings having panels of composite material, the slave bolts currently used to hold the panels to the ribs are simple bolts having a head, which in use is countersunk into the wing panel, a nut and a plastic washer arranged to go between the nut and the rib. That method suffers from the disadvantage that because the bolt head and the nut project from different sides of the panel and must both be engaged simultaneously during tightening of the bolt, in practice the bolts can only be tightened manually, with consequent delay. Furthermore, only one side of the wing skin can be worked on at one time because the space between the upper and lower wing skins is not sufficient for a person to get into to tighten the nuts. Thus, one wing skin must be disassembled before the other wing skin can be aligned with the ribs, drilled and fastened. Thus, the overall process of wing assembly is time consuming and laborious. Moreover, the manual tightening of the slave bolts undesirably brings in an element of human error.
Those problems have been partially overcome in the manufacture of wings having metal panels and metal ribs by the use of slave bolts which can be tightened and released from one side (one-sided). Various designs of such one-sided slave bolts are known but they suffer from the disadvantage that they include bulky mechanisms which, when the bolt is in place, project from the outside (that is, the accessible side) of the wing assembly, thereby preventing access for the head of the previously-mentioned automated machine.
Moreover, some of those known one-sided slave bolts are not suitable for use with composite material components because the part of the bolt which extends through the bolt hole to the inside (that is, the inaccessible side) of the component and clamps against the inside of the component, clamps against only a minor fraction of the periphery of the hole, and would therefore be likely to exert such a pressure as to damage the composite material.